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On the First Overtone Spectra of Protonated Water Clusters [H + (H 2 O) 3–5 ] in the Free‐OH Stretch Region
Author(s) -
Wu C.C.,
Chaudhuri C.,
Jiang J. C.,
Lee Y. T.,
Chang H.C.
Publication year - 2002
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200200110
Subject(s) - chemistry , overtone , anharmonicity , ion , spectral line , protonation , analytical chemistry (journal) , cluster (spacecraft) , atomic physics , triatomic molecule , infrared spectroscopy , spectroscopy , proton , inorganic compound , physics , organic chemistry , chromatography , quantum mechanics , astronomy , computer science , programming language
The gas‐phase near‐infrared spectra of protonated water clusters [H + (H 2 O) n , n = 3–5] have been obtained using a vibrational predissociation ion trap spectrometer coupled with a tunable optical parametric oscillator laser. The spectral bands in the frequency range from 7000 to 7500 cm −1 are assigned to the first overtone vibrations of non‐hydrogen‐bonded (free) OH stretches. Assignments of the spectra are made with reference to the data for H 2 O vapor, (H 2 O) 2 in Ar matrices, and considering the presence of the excess proton in the clusters. Blue shifts of the bands are observed to increase with cluster size and are interpreted in terms of a charge screening effect. The observations have allowed determination of the anharmonicity coefficients of these cluster ions on the basis of the calculations using the term value expression of vibrational energy.